//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5000 SUBJECT: GRB 060424: Swift detection of a burst DATE: 06/04/24 04:36:02 GMT FROM: Scott Barthelmy at NASA/GSFC E. Rol (U Leicester), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL) and D. E. Vanden Berk (PSU) report on behalf of the Swift Team: At 04:16:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060424 (trigger=206773). Swift was not able to slew to the burst due to its proximity to the Sun. The BAT on-board calculated location is RA,Dec 7.355, +36.820 {00h 29m 25s, +36d 49' 11"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a small spike on top of a weak peak starting about T-5 sec to about T+5 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. Because of the Sun observing constraint, there will not be any XRT or UVOT follow-up observations on this burst for at least 24 days. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5001 SUBJECT: GRB 060424: Refined analysis of the Swift-BAT burst DATE: 06/04/24 15:20:49 GMT FROM: Scott Barthelmy at NASA/GSFC D. Hullinger (BYU-Idaho), L. Barbier (GSFC), S.D. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-240 to T+734 sec from recent telemetry downlinks, we report further analysis of BAT GRB 060424 (trigger #206773) (E.Rol, et al., GCN 5000). The BAT ground-calculated position is RA,Dec = 7.354,+36.789 deg {0h 29m 25.1s,+36d 47' 20.7"} (J2000) +- 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 53%. The mask-weighted lightcurve has 5 main peaks at T-18, T-4, T+2, T+9, and T+20 sec with widths ranging from 4 to 8 sec FWHM. T90 (15-350 keV) is 37 +- 2 sec (estimated error including systematics). Swift did not automatically slew to this new burst because of the Sun observing constraint. It did slew to a pre-planned observing target at T+160 sec and the new burst went out of the BAT FOV at T+240 sec. The time-averaged spectrum from T-19.6 to T+20.6 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.19. The fluence in the 15-150 keV band is 6.8 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.11 sec in the 15-150 keV band is 1.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5003 SUBJECT: GRB060424: optical afterglow detection DATE: 06/04/25 08:25:50 GMT FROM: Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr Christina C. Thoene, Kim Nilsson, Brian L. Jensen, Johan Fynbo (Dark Cosmology Centre) report We observed the BAT error circle of GRB060424 (GCN 5000) in I with the NOT and ALFOSC on La Palma, starting at UT 05:03:40 at very high airmass. Inside the BAT revised error circle (GCN 5001) we detect a new source at the position (J2000) RA = 00:29:25.8 Dec =+36:47:58.7 The preliminary I magnitude obtained from 5x300s stacked images with a mean time of about 1h after the burst is I = 19.1 (compared to a nearby USNO star) The source is not visible in observations obtained the following night and therefore likely to be the afterglow of GRB060424 A finding chart will be available soon at: http://www.astro.ku.dk/~brian_j/grb/grb060424.178/